The invention relates to a yarn feeder for textile machines.
Yarn feeders are used to feed yarns to yarn using stations, such as individual knitting stations in loop-forming textile machines. The yarn feeders are separate devices, which must be secured in great numbers to the machine. Depending on the use, special demands may ensue for the yarn feeder that require a certain adaptation. From the standpoint of the manufacturer of the yarn feeder, it is therefore expedient if the yarn feeders are easily adaptable to different situations, which can result from the type of textile machine used in a given case or from a particular practical use. Adaptation should be feasible at the least possible expense and with the simplest possible means.
The invention is carried out by a yarn feeder having an adjustable yarn guide arrangement. The latter includes a yarn guide element, such as a yarn eyelet, which can be adjusted between two different oblique draw-off positions relative to the yarn guide drum. Drawing the yarn off obliquely enables the traveling yarn to keep the yarn guide drum clean. The adjustment is affected along a specified path. Thus the yarn guide element can be moved to at least two different positions, in which the yarn travels along the lower rim of the yarn guide drum at different angles. With a comparatively shallower payout course, that is, in a first position in which the yarn guide element is relatively high or in other words is only slightly below the lower rim of the drum, but in turn is at a greater horizontal spacing from it, the yarn being paid out separates relatively slowly from the windings located on the yarn guide drum and is then paid out along the lower rim of the drum. This prevents the situation in which the yarn being paid out could tear the windings on the yarn guide drum down along with it. In this mode of operation, the yarn feeder is especially suitable for spun yarns, in which windings located side by side adhere relatively strongly to one another because of the filaments protruding from the yarn.
In a second position, the yarn guide element is at a comparatively great vertical spacing from the lower rim of the yarn guide drum but in turn is set at a lesser horizontal spacing from the pivot axis. The yarn being paid out is drawn downward relatively steeply, so that it sweeps firmly over the lower rim of the yarn guide drum. In this mode of operation, fluff deposits and rings of fiber, which could form on the lower rim of the yarn guide drum, are swept off especially well. This operation is especially suitable for continuous-filament yarns.
The advantage of the adjustable yarn guide element is that the payout angle of a yarn guided by the yarn guide element is adjustable. If the yarn is changed, for instance by being cut upstream of the yarn feeder and with a new yarn being spliced to the remaining end of the old yarn, then the new yarn travels through the yarn feeder to the textile machine without having to be threaded in manually. The yarn guide element can be adapted accordingly in its position to the filament properties of the yarn.
Another advantage is attained if an existing yarn feeler lever (i.e. shutoff means) is capable of functioning in both adjusting positions of the yarn guide element without having to be repositioned. For instance, one yarn feeler lever is disposed such that it scans the yarn in the vicinity of a fixed yarn eyelet. Any adjustment of the yarn guide element does not substantially shift the switching point of the yarn feeler.
The yarn feeder is furthermore preferably modularly designed. The basic device has a basic carrier, which on one end has a fastening device that is arranged for connection to the textile machine, and that at a point spaced apart from this has a rotatably supported, preferably vertically disposed shaft. The shaft is arranged on one end for connection to a yarn guide drum and on its other end is provided with a drive device. This device may be embodied by a pulley or the like.
A coupling device is provided on the yarn feeder, and additional modules can be connected to it. Thus the yarn feeder can be adapted to different kinds of use by means of a plurality of modules. Beginning with a basic device, a construction kit can thus be created, with which a number of additional modules can be made. For the yarn feeder manufacturer, this means that the many types required can be made using only a few basic elements.
Essentially, the yarn feeder is formed as a basic device by the parts that are each needed in a large number of applications. These include the basic carrier, its fastening device for connection to a machine, and a rotatably supported shaft along with a drive device, and a yarn guide drum that is preferably secured interchangeably to the shaft. Additional parts are connected to the basic carrier via one or more coupling devices. The coupling devices are disposed for instance on both sides of the shaft., which makes greater freedom of design possible for the mounting of additional modules.
The coupling device is preferably assigned a retaining device, with which the counterpart is retained in its desired position. The retaining device may be a clamping device, detent device, or other kind of fastening means. The clamping device can for instance be formed by a chucking device, which deforms the guide device somewhat and thus brings about clamping by frictional engagement. The result is secure bearing of the additional module and large-area transmission of force as well as seating of the additional module without rattling. The large-area force transmission makes it possible to embody the coupling device of the same plastic as the basic carrier, even if the coupling device is required to transmit some forces.
The additional module can be provided for receiving further elements, which are preferably retained interchangeably. If the additional module is a retainer that protrudes freely, for instance, then different yarn guide elements can be secured to it. Bearings for further supporting the shaft on the retainer can also be provided, if necessary.
Another additional module may for instance be a yarn brake. Depending on the application, various types of brake can be kept on hand (driven, nondriven, with magnetic clamping of the brake elements, spring clamping, etc.). A further fixture module may be a friction module, which in addition to a friction drum that feeds the yarn by frictional engagement has means for defining the wrap angle of the yarn around the yarn guide drum. For bearing the yarn guide means or similar parts that belong to the friction drum, suitable connection means may also be provided on the underside of the basic carrier. The basic carrier is preferably formed by a two-shell housing, which is divided approximately horizontally. The housing parts are then separably joined to one another, and as a result the housing interior becomes accessible. Additional devices, such as electric switches, circuits, bearings for yarn feeler levers and the like, can be accommodated in the housing interior.